Heat sink



FIG. 1 is a front elevational view of a heat sink;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a front, bottom, and right side perspective view thereof;

FIG. 7 is a rear, bottom, and left side perspective view thereof; and,

FIG. 8 is a rear, bottom, and right side perspective view thereof.

Any portion of the top of the heat sink not shown in the drawings forms no part of the claimed design.

The broken lines in the drawings depict environmental subject matter only and form no part of the claimed design. 

CLAIM The ornamental design for a heat sink, as shown and described. 